Mercaptobenzothiazole disulphide

Because of their high molecular weight, the hydroxy-terminated polymers are difficult to process and a chemical plasticizer is usually added to facilitate milling. The plasticizer is a disulphide such as benzothiazyl disulphide (mercaptobenzothiazole disulphide, MBTS) interchanges of the following type... 

In sulphur cured rubbers, accelerators are generally used to reduce the dependency on sulphur in order to achieve more efficient vulcanisation, to improve heat and flex resistance due to the presence of more monosulphidic crosslinks, and to increase the cure rate of the rubber and improve production capacity. Two accelerators which have been shown to enhance bondability of rubbers are 2-mercaptobenzothiazole (MBT) and mercaptobenzothiazole disulphide (MBTS). An accelerator which is known to negatively impact on adhesion is tetramethyl thiuram disulphide (TMTD). 

BDTPTS bis(di-ethyl thiophosphoryl) trisulphide CBS N-cyclo hexyl benzthiazyl sulphenamide MBTS mercaptobenzothiazole disulphide NOBS N-oxy di-ethylene benzthiazyl sulphenamide TMTD tetra-methyl thiuram disulphide DBG N, N diphenyl guanidine ... 

With the sulphur-modified polymers cure may be brought about by zinc oxide and magnesium oxide in combination either alone or together with an accelerator such as ethylene thiourea. In the case of the homopolymers it has been common practice to support the zinc oxide/magnesium oxide/ethylene thiourea system with a further component. This component consists of a sulphide or a blend of sulphides of the type more commonly used as accelerators for the diene hydrocarbon polymers. These include mercaptobenzothiazole disulphide (MBTS), diorthotolyl guanidine (DOTG) and tetramethyl thiuram monosulphide (TMTM). In the polychloroprene homopolymers these materials appear to act as retarders of cure at processing temperatures but are accelerators at vulcanization temperatures. Their mechanism does not appear to have been fully elucidated. 

A further, important, component is an accelerator similar to those used with diene rubbers, e.g. mercaptobenzothiazole disulphide (MBTS). Its main function appears to be to prevent radical-initiated decomposition of the sulphonyl chloride grouping, a process which not only removes a sulphonyl cure site but which also generates acidic gases ... 

TBBS A/-t-ButyIbenzothiazole-2-su(phenamide MBTS Dibenzothiazole di.sulphide MBT 2-Mercaptobenzothiazole TMTD Telrainethythiutam disulphide... 

The synthesis of tazobactam from 6-APA (Scheme 6.15) proceeded via the 2- -(chloromethyl)penam ester (81 a), which was first prepared by Gottstein and co-workers [47] during the synthesis of 2-/S-(chloromethyl)-2-a-methylpenam-3a-carboxylic acid 1,1-dioxide (29). 6-APA (8) was converted to 6a-bromopenicillanic acid (77) by treatment with sodium nitrite and hydrobromic acid. Oxidation with peracetic acid in the presence of benzophenone hydrazone gave benzhydryl 6a-bromopenicillanate-l-oxide (78) and reduction with zinc and acetic acid gave benzhydryl penicillanate-1-oxide (79). The unsymmetrical azetidinone disulphide (80) was obtained by heating with 2-mercaptobenzothiazole reaction with copper (II) chloride... 

Aminopenicillanic acid (8) was converted to 6(5)-bromopenicillanic acid by trapping of the diazo-intermediate with hydrogen bromide. Esterification of the dicyclohexylamine salt (93) with p-methoxybenzyl bromide, followed by oxidation, afforded the sulphoxide (94) in 60% yield from 6-APA. Elaboration of this sulphoxide to the disulphide (96) was effected by the procedure established by Kamiya et al. [98] the sulphenic acid (95), formed by heating the sulphoxide to reflux in toluene, was intercepted by reaction with 2-mercaptobenzothiazole to yield the disulphide (96). The latter was transformed by base-catalysed double bond isomerization to the conjugated ester disulphide (97) [95% yield from (94)]. Reductive formylation of disulphide (97) then provided the formylthio-derivative (98). Cyclization of the oxalimide (99), obtained by ozonolysis of... 

TBBS -l-ButyIbenzothiazole-2-sulphenamide MBTS Dibenzothiazole disulphide MBT 2-Mercaptobenzothiazole TMTD Teiramethythiurain disulphide... 

Reactions of 2-Mercaptobenzothiazoles. The (un)substituted 2-mercapto-benzothiazoles react with an amine and O2 in the presence of HjO and cobalt phthalocyanine to give high yields of sulphenamide (213) they also react with morpholine in the presence of NaOCl. These sulphenamides could be the first step in the conversion into disulphides (214). The 2-mercaptobenzothiazoles are substituted in alkaline solution with halo-compounds. ... 

From Benzothiazolyldithioazetidinone Type C). The disulphides (6), which are obtained by the reaction of penicillin sulphoxides and 2-mercaptobenzothiazole, give different products with bases, dependent on the structure of the substituents on the -lactam nitrogen e.g., [6 R = CH(C02H)C(Me)=CH2] gives (7) whilst [6 R = C(=CH2)C02CH2CCl3] gives (8). "... 

Fig. 12.5. Dependence of tensile strength (Ts) on cross-link density (vt) and cross-link structure for (a) EPDM (Royalene 301) and (b) EPM (Dutral). Tested using dumbell type 3 at 250mm/min elongation rate at 20 C. Cure systems (a) EPDM (1) tetramethylthiuram disulphide, bis (benzothiazolyl) disulphide (2) dicumyl peroxide, 1 phr sulphur (3) dicumyl peroxide, 0 3 phr sulphur (4) mercaptobenzothiazole (5) dicumyl peroxide (b) EPM (1) dicumyl peroxide, 1 phr sulphur (2) dicumyl peroxide, 0-3 phr sulphur (3) dicumyl peroxide. (From Imoto et al, 1%8.)...

Journal of Applied Polymer Science 76, No.9, 31 St May 2000, p. 1413-21 BENZOTHIAZOLE-ACCELERATED SULPHUR VULCANISATION. V. 2-BISBENZOTHIAZOLE-2,2 -DISULPHIDE/ZNO AND 2-BISBENZOTHIAZOLE-2,2 -DISULPHIDE/(2-MERCAPTOBENZOTHIAZOLE)ZINC(ll) AS ACCELERATORS FOR 2,3-DEMETHYL-2-BUTENE... 

The results are reported of a study of accelerated sulphur vulcanisation using the above compounds. 2,3-Dimethyl-2-butene, was utilised as a model compound for polyisoprene and residual curatives, intermediates and products produced by heating the mixes for various times at 150C in sealed tubes were analysed using high-performance liquid chromatography. A synergistic effect was observed between bis(2-mercaptobenzothiazole) zinc(II) and 2-bisbenzothiazole-2,2 -disulphide. 23 refs. SOUTH AFRICA... 

Details are given of nitrosamine formation in twenty-nine different EPDM cures. Both ingredient and process-related effects were investigated. Two different levels of tetramethylthiuram disulphide and carbon black were variables in this study, as was the type of carbon black used. Batch effects with respect to both polymer and carbon black were also studied as was the presence or absence of mercaptobenzothiazole. 14 refs. 

Investigations were carried out with the binary combinations of each of bis(N-methylpiperazino)thiuram disulphide, tetrabenzylthiuram disulphide, and tetramethylthiuram disulphide, separately with N-cyclohexyl-2-benzothiazole sulphenamide, 2-mercaptobenzothiazole, and 2-mercaptobenzothiazyl disulphide in the combinations studied. 19 refs. 

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